sensation and perception Flashcards
(20 cards)
sensation
Sensation: the information that we receive through our senses
- special sensory organs detect information from outside world inside our bodies and convert that into tiny electrical signals
that process is called transduction
perception
Perception: how we interpret or make sense of the sensory information that we receive.
- If we pay attention to everything, we would receive a lot more information than we could cope with. We hear lots of sounds, see things that don’t matter.
visual perception
Visual Perception: how we perceive the information received by our eyes
-when we use our eyes, sensory organs receive information about lightness, darkness, and colour, which is picked up as tiny dots. Each sense receptor picks up just the information from one little part of the whole visual field you can see.
- We do not see a mass of tiny dots, even though that is what our visual receptors receive. We see patterns, shapes, people, and things clearly or faintly.
- Sometimes don’t even see a proper shape, but our experience allows us to make it out so we can see what is there.
depth cues (judging distance)
- The image that our eyes receive is two-dimensional (we live in 3D world) to avoid bumping into things, we need to know how far they are.
-Judging distance is something we do without thinking
We do it by using key bits of information known as depth cues
depth cues
Depth cue: a feature of an image which indicates distance
Monocular depth cue: a way of detecting depth or distance, which requires just one eye.
Binocular depth cue: a way of detecting depth or distance, which requires two eyes.
monocular depth cues
height in plane: how high the object appears in the image
relative size: how large an object appears in an image
occlusion: when one object seems to cover part of another object
linear perspective: when straight lines are angled so that they would come together at a point on the horizon.
binocular depth cues
Uses two eyes, two images (nearly the same), compares them, works out how far away things are.
More accurate in our judgements of depth.
Convergence: a form of depth perception, which uses how eye muscles focus on images.
- We focus our eyes differently to see things that are close to how we focus to see things further away.
Retinal disparity: a form of depth perception which compares the images from two eyes side by side.
- If something is close to us, there is quite a difference in what the two eyes see
- if it is further away, less of a difference between the two images: after about 10 metres, the difference is hardly noticeable
visual illusions
Visual Illusions: a visual perception which is wrong or misinterprets what is actually there in reality.
why do visual illusions happen
This can happen for several reasons, including:
-Misinterpreted depth cues: wrongly applying the rules of depth perception.
-Ambiguity: when an image could actually be one thing or another.
- Fiction: creating something that isn’t there really there to complete an image.
- Size constancy: keeping our original perception of the size of an object, even when the information received by the eyes changes.
perceptual set
Perceptual set: a state of readiness to perceive certain kinds of stimuli rather than others.
To be set means to be fully ready and prepared, facilitating what is coming so we can do it effectively.
Our cognitive processes—memory, decision-making, and perception—can be affected by set.
Example: babies learn rhymes more easily than other sentences because they are set to learn through repetition. We are more likely to perceive things if our perception is set to notice that kind of thing.
what factors affect our perception: expectation
Expectation: the beliefs we have about what we are going to experience
E.g., people who have been shown pictures of birds’ heads are set to see birds’ heads; if they are shown figure a, they often say it’s a duck’s head because they expect to see more birds’ heads. However, if they had seen pictures of rabbits’ heads, they would have probably given a different answer.
what factors affect our perception: culture
Culture: A group of people who share similar customs and beliefs which influence how we make sense of what we are seeing.
In modern western society we grow up with lots of line drawings, cartoons—not particularly realistic, but we are used to them, they are often in children’s books. If they are asked to draw an animal, they usually draw it from the side.
- doesn’t apply to children who have grown up in traditional tribal societies, where they don’t have picture books or cartoons.
- If they are asked to draw an animal, they usually draw it from the front because they are drawing what they perceive, which is what the animal they know has a head, trunk, or legs.
- Perception of western children has been shaped by their exposure to line drawings so they draw what looks like the side of the animal.
Children from traditional environments realize they are meant to be an animal even if it looks incorrect.
what factors affect our perception: expectation: emotion
Emotions: the moods or feelings that a person experiences.
These emotions influence what we perceive and contribute to our perceptual set.
E.g., someone who is upset is more likely to notice upsetting actions or events, and they won’t notice positive things that are happening.
what factors affect our perception: motivation
Motivation: the drives and needs that cause a person to act in a particular way.
We have lots of different types of motives, ranging from physical motives, like being hungry or thirsty, which encourage us to eat or drink , to social, like wanting to keep in with our friends or looking for respect from other people.
In those cases, we often notice any little detail of other people’s actions that fit with our motivation, and ignore any information which doesn’t.
the ponzo illusion
- Linear perspective
- The two other lines of drawings create an illusion of perspective.
- Unconsciously, we see the top inner line as being further away from the bottom line as we perceive it as longer.
- But if we measure the lines, they are exactly the same.
the muller-lyer
- Linear perspective, size constancy
- With the left line, the outward points (arrows) seem to be ‘pushing’ the line towards us whereas the inward points (arrows) on the right line suggest that it is further away.
- Because we perceive the left line as being closer, we see it as shorter than the other one.
rubins vase
- Ambiguity
- It might be a vase, or it might be two faces seen from the side.
- We can see either the vase or the faces, but not both at the same time.
If we look at the faces, the vase disappears. In this case, the brain copes with the ambiguity by focusing on one interpretation of the other.
the necker cube
- Ambiguity
- It seems to flip backwards and forwards.
- The drawing is perfectly balanced, that is, it can be seen either way – so your brain can’t decide which is the ‘right’ way round.
- Both hypotheses are equally possible, and therefore, it flips the perceived image from one to the other.
the kanisza triangle
- Fiction
- The triangle is not really there – it is fiction our perception has created, suggested by the shapes around it, but appears so clearly it even appears to stand out of the proper figure.
- The perceptual system generates an image which fills in the gap to create something plausible
ames room
- Size constancy
- If we look at it from a special viewpoint, we see one person as being much larger than the other.
It works because although the room looks square, it isn’t really. - The person who looks smaller really is further away, but the lines in the room are carefully drawn so the viewer doesn’t see it that way.
